1. Field of the Invention
This invention relates to a non-page type, e.g., a serial or line type printer having a function of receiving and printing print information produced in accordance with a page describing language and transferred thereto from a host computer.
2. Description of the Related Art
Conventionally, a page describing language is contrived in order to raise the degree of freedom of a print format and unify standards of a data transfer sequence between a host computer and a printer in the field of printing wherein a page printer such as a laser printer is used.
In recent years, a page printer having a page describing language built therein has such a construction as shown in FIG. 3. In the construction, reference numeral 10 denotes a host computer, and 11 a page printer unit.
The host computer 10 and the page printer unit 11 have data transferring/receiving means therein and are connected to each other.
Meanwhile, the page printer unit 11 is constituted from a page describing language interpreting section 1, a page memory 2, and a print controlling section 12. The host computer 10 transfers copy data produced in accordance with a format of the page describing language to the page printer unit 11 by way of the data transferring means. The transfer data received by the page printer unit 11 are transmitted to the internal page describing language interpreting section 1, in which the page describing language is interpreted and converted into data of a dot image necessary for the final printing, and the data from the page describing language interpreting section 1 are stored into the page memory 2 which has a capacity for one full page. Print information produced in accordance with the page describing language and transferred from the host computer 10 is sequentially converted in accordance with the procedure described above, and at a point of time at which preparation of image data for one page is completed, the data are transferred to the print controlling section 12 so that results of printing can be obtained.
However, in the conventional page printer described above all print data produced in accordance with a page describing language are normally developed finally as image data in which there is no distinction between character data and graphic data. Thus, the following problem arises when a page describing language is used with a non-page type printer, e.g., a serial printer.
Generally, upon printing with a serial type printer, the number of scanning strokes of a print head with respect to a print medium is constant. In particular, since the feeding amount of a print medium for each scanning stroke is constant, when character data are to be printed, codes or font data which can be identified by a print controlling section are transferred from a host computer to a printer and printed in a single scanning stroke, and accordingly, they will not be printed over two scanning lines. However, print data produced in accordance with a page describing language are so high in degree of freedom that character data may not always remain on a predetermined scanning line. Since data are transferred as image data to a printer, character data may be printed in two upper and lower portions over two scanning lines as seen in FIG. 4. Consequently, there is a problem in using a page describing language with a serial printer or line printer in that displacement of dots which relies upon an accuracy of controlled operation to move a print head in a vertical direction (relative to the print medium) may take place and, as for character data, the print quality regarding character data may be deteriorated as compared with a page printer.